1. Field of the Invention
The present invention relates to a storage system for storing data on hard disk drives. More specifically, the present invention relates to a storage system for inputting/outputting block-basis data as well as file-basis data.
2. Description of Related Art
In the current information-oriented society, with the prevalence of inter-corporate electronic commerce by using the Internet and inter-corporate links, typically, supply chain management, making good use of data is important in corporate strategy.
Storage systems for storing information facilitate IT platforms connection and operation.
With the explosive increase of data amount, the cost required for maintaining and managing storage systems increases significantly.
Corporations tend to gather storage systems and servers connected thereto in a data center, apply centralized management of databases such that kinds of servers can access to the databases and share data so as to reduce Total Cost of Ownership (TCO) by simplifying the operation, maintenance and management of the overall system.
As a method for allowing different kinds of servers to access storage systems and share the data stored in these systems, a Storage Area Network (hereinafter abbreviated to SAN) is developed. The SAN is the network dedicated to storage using fiber channels, each of which provides an interface connecting a server and a storage system, and a switch for fiber channels. The SAN thus makes multipoint-to-multipoint connections between a plurality of servers and a plurality of storage systems.
Applications to run on servers handle file-basis data, whereas storage systems connected to the SAN, typically a disk array, operate for block-basis data input and output.
Thus, when data input/output between a server and a storage system is performed, a file system on the server translates file-basis data to block-basis data that is input via the SAN to the storage and translates block data output via the SAN from the storage to file data.
Meanwhile, Network Attached Storage (hereinafter abbreviated to NAS) has bercome prevalent as another method for allowing different kinds of servers to access storage systems and share the data stored in these systems.
The NAS has a file system within the storage system, and file-basis data input/output is performed between a server and the NAS. The file system within the NAS translates file-basis data to block-basis data that is stored on a hard disk drive.
Thus, the NAS is connected to a Local Area Network (“LAN”) that is popular as a general network for server-to-server communication.
As described above, the SAN and NAS become prevalent as the means for sharing data. Such an environment as is schematized in FIG. 2 where a storage system, typically, a disk array system 6, connected to a fiber channel based Storage Area Network (FC-SAN) 2 coexists with a NAS 7 connected to a LAN 3 in a data center.
While the SAN is the fiber channel based network for carrying block-basis data as described above, standardizing the procedure for block-basis data input/output between the storage system and host servers is by the Internet Protocol (hereinafter abbreviated as “IP”) that is generally used for the communication between the host servers 1 via the LAN 3. In future, an Ethernet based SAN 9 (FIG. 3) is expected to become popular.
In future, such an environment is expected to be what is in the topology schematized in FIG. 3 where a disk array system 6 and a NAS 7 coexist.
Since the NAS connected to the LAN 3 may transmit and receive a great deal of data to/from the host server 1, the increased load on the LAN 3 affects the communication between the host servers 1.
If the Ethernet based SAN 9 becomes prevalent, it is conceivable that the NAS 7 be connected to the Ethernet based SAN 9 in the topology shown in FIG. 3.
As shown in FIGS. 2 and 3, the environment where the disk array system 6 and the NAS 7 coexist in a data center is expected to become popular in future, though the topology may be in various forms. In such environment where different types of systems exist separately, system maintenance and management will become complex.
Because both the disk array system 6 and NAS 7 store block-basis data on hard disk drives, it is theoretically possible for them to share the drives to store data. However, it is difficult to share the drives because they were conventionally separate systems.
The NAS transmits and receives data to/from other storage systems with the intervention of a file system. Consequently, the NAS is slow data backup and copy speed in comparison with storage systems such as disk array systems that directly transmit and receive block-basis data between them without the intervention of the file systems.